Vergleichende Analyse von Simulationstechniken für maßgefertigte Endoprothesen
Background
The technical success of fenestrated endovascular aortic repair (FEVAR) depends on the precise fit of the custom-made endograft in the patient. Software for numerical simulations (PlanOp AI, PrediSurge) is available for the digital verification of the planned prosthesis design.
Methods
The distance between opposing tips of the proximal sealing ring of the endograft was measured using computed tomography (CT) scans of the test implantation in a 3D-printed model, by means of numerical simulation software, and using postoperative CT scans.
Two types of modeling were used for the aorta in the numerical simulation software: rigid and deformable. This resulted in four measurements:
- CT scan of the physical endograft prototype implanted in a rigid, printed silicone model of the aorta.
- Rigid numerical or finite element (FE) simulation of the endograft implanted in a rigid aortic model.
- Numerical or FE simulation with a deformable virtual aortic model and
- Postoperative CT of the patient.
Results
Ten patients were included in the study. The mean distance between the tips in the postoperative CT scan (reference) was 26.8 mm. The distance in the rigid printed model was 23.8 ± 2.0 mm p< 0.003).
The FE analysis with a rigid aorta resulted in 23.8 ± 1.5 mm (p< 0.006). The measurements from the CT of the physical prototype tested in the printed silicone model of the aorta and the measurements from the FE analysis with rigid modeling did not differ significantly. The measurements in a simulated deformable aorta resulted in 27.4 ± 2.1 mm (p < 0.521).
Eine hohe Korrelation (r = 0,81, p< 0,01) wurde zwischen den Messungen im postoperativen CT und der FE-Analyse der deformierbaren Aorta festgestellt.
Fazit
Die numerische Simulation mit einer starren Aorta kann ein geeigneter Ersatz für die herkömmliche Testimplantation eines unsterilen Prototyps in einem 3D-Aortenmodell sein.
Dies kann dazu beitragen, den Zeitaufwand für die Planung und Anfertigung von Prothesen zu reduzieren. Die FE-Analyse mit einer deformierbaren Aorta konnte die Abstände zwischen den Spitzen am proximalen Dichtungsring zuverlässiger vorhersagen.
Die Auswirkungen auf die klinischen Ergebnisse und das Auftreten von Endoleaks müssen in zukünftigen Studien noch geklärt werden.